[PATCH 3/3] staging/lustre, 9p, ceph, cifs, dlm: negate remote pids for F_GETLK

[Benjamin Coddington]

In the previous patch, the locks API will expect that if a filesystem
returns a remote pid as opposed to a local pid for F_GETLK, that remote pid
will be <= 0.  This signifies that the pid is remote, and the locks API
will forego translating that pid into the pid namespace of the local
calling process.  Since local pids will never be larger than PID_MAX_LIMIT
(which is currently defined as <= 4 million), but pid_t is an unsigned int,
we should have plenty of room to represent remote pids with negative
numbers if we assume that remote pid numbers are similarly limited.  If
this is not the case, then we run the risk of having a remote pid returned
for which there is also a corresponding local pid.  This is a problem we
have now, but this patch should reduce the chances of that occurring, while
also returning those remote pid numbers, for whatever that may be worth.

This patch updates lustre, 9p, ceph, cifs, and dlm to negate the remote pid
returned for F_GETLK lock requests.

Signed-off-by: Benjamin Coddington <bcodding@xxxxxxxxxx>
---
 drivers/staging/lustre/lustre/ldlm/ldlm_flock.c | 2 +-
 fs/9p/vfs_file.c                                | 2 +-
 fs/ceph/locks.c                                 | 2 +-
 fs/cifs/cifssmb.c                               | 2 +-
 fs/dlm/plock.c                                  | 2 +-
 5 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/staging/lustre/lustre/ldlm/ldlm_flock.c b/drivers/staging/lustre/lustre/ldlm/ldlm_flock.c
index b7f28b39c7b3..abcbf075acc0 100644
--- a/drivers/staging/lustre/lustre/ldlm/ldlm_flock.c
+++ b/drivers/staging/lustre/lustre/ldlm/ldlm_flock.c
@@ -596,7 +596,7 @@ ldlm_flock_completion_ast(struct ldlm_lock *lock, __u64 flags, void *data)
 		default:
 			getlk->fl_type = F_UNLCK;
 		}
-		getlk->fl_pid = (pid_t)lock->l_policy_data.l_flock.pid;
+		getlk->fl_pid = -(pid_t)lock->l_policy_data.l_flock.pid;
 		getlk->fl_start = (loff_t)lock->l_policy_data.l_flock.start;
 		getlk->fl_end = (loff_t)lock->l_policy_data.l_flock.end;
 	} else {
diff --git a/fs/9p/vfs_file.c b/fs/9p/vfs_file.c
index 3de3b4a89d89..43c242e17132 100644
--- a/fs/9p/vfs_file.c
+++ b/fs/9p/vfs_file.c
@@ -288,7 +288,7 @@ static int v9fs_file_getlock(struct file *filp, struct file_lock *fl)
 			fl->fl_end = OFFSET_MAX;
 		else
 			fl->fl_end = glock.start + glock.length - 1;
-		fl->fl_pid = glock.proc_id;
+		fl->fl_pid = -glock.proc_id;
 	}
 	kfree(glock.client_id);
 	return res;
diff --git a/fs/ceph/locks.c b/fs/ceph/locks.c
index 6806dbeaee19..0fd5c288ce4e 100644
--- a/fs/ceph/locks.c
+++ b/fs/ceph/locks.c
@@ -79,7 +79,7 @@ static int ceph_lock_message(u8 lock_type, u16 operation, struct file *file,
 	err = ceph_mdsc_do_request(mdsc, inode, req);
 
 	if (operation == CEPH_MDS_OP_GETFILELOCK) {
-		fl->fl_pid = le64_to_cpu(req->r_reply_info.filelock_reply->pid);
+		fl->fl_pid = -le64_to_cpu(req->r_reply_info.filelock_reply->pid);
 		if (CEPH_LOCK_SHARED == req->r_reply_info.filelock_reply->type)
 			fl->fl_type = F_RDLCK;
 		else if (CEPH_LOCK_EXCL == req->r_reply_info.filelock_reply->type)
diff --git a/fs/cifs/cifssmb.c b/fs/cifs/cifssmb.c
index fbb0d4cbda41..cb367050f972 100644
--- a/fs/cifs/cifssmb.c
+++ b/fs/cifs/cifssmb.c
@@ -2515,7 +2515,7 @@ CIFSSMBPosixLock(const unsigned int xid, struct cifs_tcon *tcon,
 			pLockData->fl_start = le64_to_cpu(parm_data->start);
 			pLockData->fl_end = pLockData->fl_start +
 					le64_to_cpu(parm_data->length) - 1;
-			pLockData->fl_pid = le32_to_cpu(parm_data->pid);
+			pLockData->fl_pid = -le32_to_cpu(parm_data->pid);
 		}
 	}
 
diff --git a/fs/dlm/plock.c b/fs/dlm/plock.c
index d401425f602a..e631b1689228 100644
--- a/fs/dlm/plock.c
+++ b/fs/dlm/plock.c
@@ -367,7 +367,7 @@ int dlm_posix_get(dlm_lockspace_t *lockspace, u64 number, struct file *file,
 		locks_init_lock(fl);
 		fl->fl_type = (op->info.ex) ? F_WRLCK : F_RDLCK;
 		fl->fl_flags = FL_POSIX;
-		fl->fl_pid = op->info.pid;
+		fl->fl_pid = -op->info.pid;
 		fl->fl_start = op->info.start;
 		fl->fl_end = op->info.end;
 		rv = 0;
-- 
2.9.3